Our perception is of a seamless visual world, but in reality a sharp image is available only at the very centre of gaze. Accurately planned eye movements are vital to explore our visual environment.

Why do we make errors in perception, in memory, and in our actions? Variability and uncertainty are fundamental aspects of human behaviour, which worsen with advancing age or neurological disease. In the lab we measure these factors using visual psychophysics and memory tasks, eye tracking and limb motion-tracking. Then, using mathematical models and computer simulations, we develop and test hypotheses about the underlying brain mechanisms.

One focus of the lab is on visual memory. Our ability to remember what we have seen is surprisingly limited: rather than a fixed capacity on how many objects we can remember, our work shows that the limit is on the resolution with which visual information can be maintained. Visual memory acts like a resource that can be allocated to important information in our environment: we investigate how this resource is distributed between features of the visual scene and how it is updated when we move our eyes.

Reaching movements to a remembered target. Increasing the number of locations held in memory at one time (from left to right; other targets not shown) results in increasing variability in recall.

In everyday life, we shift our gaze several times per second in order to extract detailed information from the world around us. These movements represent a simple case of exploration and decision-making behaviour. A second focus of our research is to understand the processes that decide where, when and in what order eye movements are directed.

In the brain, information about our environment and our planned actions is represented by the electrical activity (“spiking”) of neurons. Some of the most recent work in the lab involves developing computational models of encoding and decoding of neural activity that explain aspects of human perception and behaviour.

News

January 2018Reassessing the evidence from imaging data for a fixed item limit in working memory - new paper in Cerebral Cortex [pdf]

August 2017As of 2017, we will be making all data from our published studies publicly available via our publications page [link]

April 2017The population coding model of working memory explains why people make binding ("swap") errors -- new article in Journal of Neuroscience [pdf]

March 2017New article in PLOS Computational Biology examines the fidelity with which we store information about reward [pdf]

February 2017New code is available for trial-by-trial estimation of mixture component probabilities in working memory tasks [code]

January 2015Investigating the theoretical basis of misbinding in working memory, in collaboration with Loic Matthey and Peter Dayan [pdf]

December 2014EyeSearch [link] is a web-based therapy for patients with visual disorders, developed in collaboration with Alex Leff and Masud Husain — our new paper [pdf] reports benefits for visual search ability in hemianopic patients

November 2014Paul and Leonie at the Society for Neuroscience meeting in Washington DC — Leonie's poster: "Are there shared resources for motor planning?" [details]

March 2014New article in Journal of Neuroscience [pdf]: errors in short-term memory are explained by noise in neural activity

February 2014Review paper on changing concepts of working memory [pdf] in Nature Neuroscience